Specially consulted the predecessors in HDRoad, the answer is as follows: the number of source files that can be combined into a complete seed is an integer part of health, and the proportion of all data in the whole seed file size is a decimal part of health after removing the remaining duplicate data.
Health greater than 1 means that all users have complete files. Even if there are no seeds, as long as no one quits, everyone has the hope to download complete files. If it is less than 1, you will never have a chance to download all the data if no new people join.